The present invention relates to a two-speed gearbox, and more particularly to a two-speed gearbox having a locking differential for a heavy hybrid electric vehicle.
There is an increasing demand for the use of hybrid electric driven and hybrid electric assisted vehicles. Hybrid electric vehicle typically utilize motor driven axles which are often of a multi-axle configuration in military and specialty vehicles systems.
The electric motors are typically sized to meet both torque and speed requirements which may not be the most effective for the operational requirements of such vehicles. Relatively large electric motors are often utilized to meet the torque requirements which may result in an oversized motor for most operational conditions. Moreover, the relatively large electric motors may be difficult to package in a multi-axle configuration. A lightweight and compact reduction gearbox which allows the usage of relatively smaller electric motors is therefore desirable. Two speeds are particularly desirable for military and specialty vehicles to provide high torque in off road conditions and high speed for movement over roads.
Military and specialty vehicles systems also typically require the added traction provided by a biasing or locking differential. A full time biasing differential may be undesirable in such vehicle since a primary motivation for transition to hybrid electric driven vehicles is improved fuel economy which provides increased range and reduced logistic footprint.
Accordingly, it is desirable to provide a lightweight and compact two-speed reduction gearbox and on-demand biasing differential which may be utilized with a relatively smaller electric motor for incorporation into a multi-axle military and specialty vehicle system.